Crown-pin extractor.



P. H. SKINNER. GROWN PIN EXTRAGTOR. APPLICATION 311,31) SEPT. 2, 1908.

1 ,O'72,5 1 7, Patented Sept. 9, 1913.

' COLUMBIA PLANouRXPl CO.,WASH|NOTON. D. c-

To all whom it may concern Be it known that I, FRANK H. SKINNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Crown-Pin tractors, of which the following is a specification. v

My invention relates to dental instruments and has particular reference to devices for removing crown pins. I

The object of the invention is to provide an improvement upon the vise-jaw type of this class of tools, wherein the aws are connected by a common base which has served to hold the jaws apart in a normally open position, to open the closed jaws vwhen released and to support the screw for operat ing a post between the jaws.

In the present invention the above-mentioned base is relieved of the jaw-operating function, thus obviating the necessity of making the base out of metal adapted to withstand the bending strains imposed by the opening and closing of the jaws, and allowing greater latitude in the selection of material. To this end I have, in my present invention, made the jaws and base in two pieces, the base forming an integral part of one jaw while the other end is pivoted to the free end of the base. This construction not only relieves the base of the bending strains and liability to breakage therefrom, but also permits a larger relative movement of the jaws. I

With the above-named objects in view my invention consists in the novel construction, combination and arrangement of parts hereinafter described in detail, illustrated in the drawing and incorporated. in the appended claims.

In the drawing Figure 1 is a side elevation of a tool embodying my invention. Fig. 2 is edge elevation of same. Fig. 3 is a section taken on line X-X of Fig. 1. Fig. 4 is a perspective viewof the post.

In the several views 2 represents one of thej aws of the tool having the integral curved base 3 in which is jo-urnaled a screw 41- provided with a thumb head 4. This screw has threaded engagement with a hollow post 5 terminating in a pair of prongs 6 and 7, one for each side of the plane of movement of the jaws 2 and 3. At 8 the Specification of Letters Patent.

Application filed September 2, 1908.

CROWN-PIN EXTRAGTOR.

Patented Sept. 9, 1913. Serial No. 451,304.

companion jaw 9 is pivoted to the free end of the base 3, which permits the jaws to move relatively to each other to the desired. extent without imposing any strain upon the base 8. r I

In Fig. l a crown pin 10 is shown in dot ted lines in a dotted tooth 11. The jaws are, as shown, clamped upon the pin 11 by means of a clamping screw 12 which passes through an opening in the jaw 9 and has threaded engagement with a threaded bore in the jaw 2. By relieving the base of the spring function it may be made as thick and strong as desired, or, in other words, its construction need not be limited to any elastic quality and proportion. The head of the screw 4 supports the latter on one side of the base against longitudinal movement in one direction, and against movement in the opposite direction the screw is held by a collar 13 secured thereto on the opposite side of the base as shown. The clamp screw 12 supports the post5 laterally in a plane at right angles to the plane of movement of the aws 2 and 9 by its engagement of a slot 1% in the post shown in Fig. 4. Between said slot and the tips or prongs 6 and 7 is a bridge 15 which supports the prongs against spreading apart. The jaws, being set apart by the wide base 3, are capable of taking a very firm pinch hold upon a dowel or crown pin with the extreme tips of their beaks curved toward each other. The screw 4-, being journaled in the base 3 and telescoping the post, also materially assists in supporting the post in proper alinement with the jaws of the tool.

I claim as my invention-- 7 In combination with the jaws, of a base common to both said jaws, said base being an integral portion of one of said jaws and having a pivotal connection with the other jaw, a screw for moving said jaws, a post having a part engaging said screw and having another part adapted to rest upon the root of a tooth, and a post-actuating screw mounted in said base between said jaws.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

FRANK H. SKINNER. Witnesses:

EDWARD P. SKINNER,

C. Gr. Noyes. 7

Copies of this patent maybe obtained for five cents each, by addressing the Commissioner of Patents, 

